UM1491

Board architecture

Doc ID 022479 Rev 1

13/25

7.2

Gate driving

As mentioned previously, gate driving of the switches is performed by the latest of the L6390

family of devices. Refer to

Section 8.1 for detailed information on the gate driving circuit and

dead-time insertion. A fault signal is also fed back to the J5 connector if an overcurrent event

is detected.

7.3

Amplifying network

The voltages across the three shunt resistors are amplified by K to correctly condition the

current feedback signals and optimize the output voltage range for a given phase current

range and A/D converter input dynamics. Refer to

Section 8.3 for more detailed information

on how to dimension the op-amp conditioning network depending on your needs.

7.4

Brake feature

The brake feature performs motor braking by switching simultaneously to the low-side power

MOSFET, thus shortening the motor phases.

Warning:

This feature is mandatory in applications that require the

motor to operate in a flux-weakening region. In these

conditions, the back-EMF generated by the rotor’s spinning is

greater than the bus voltage, and the brake feature prevents

the motor from acting as a generator and destructively

charging the bus capacitance. Refer to

Section 8.4 for

additional information.

7.5

Temperature feedback

Temperature feedback is performed by way of an NTC. It enables monitoring of the power

stage temperature so as to prevent any damage to the inverter caused by overtemperature.